1. Field of the Invention
This invention generally relates to a soil treatment apparatus. More specifically, the present invention relates to a soil treatment apparatus traversable across the soil in a driving direction.
2. Background Information
A soil treatment apparatus is traversable across the soil in a driving direction. This can be realized, for example, by configuring the soil treatment apparatus for linkage mounting on a tractor, or to form it as an automotive unit, or even as a push unit for pushing from behind or as a pull unit for pulling in front or, more generally, as a hand-operated apparatus.
The soil treatment apparatus is provided, in particular, for soil aeration and has a plurality of tool units for this purpose. From U.S. Pat. No. 4,632,189, a soil treatment apparatus having plunger tools moveable up and down by means of a bracket is known. Here again, a plurality of tool units is provided. A single stop beam against which all plunger tools abut, is also pivotally linked to the chassis. The stop beam has only two possible positions, as it is pivotal between an operating position and a rest position. In the rest position all plunger tools are folded to the top, so that the brackets can be further driveably moved without the plunger tools plunging. This has the sole purpose of driving across the soil without the plunging function, for example, when a paved path or the like has to be crossed. This construction entails that the plunger tools rub along the stop common to all plunger tools, which is a drawback with respect to abrasive wear. Moreover, no well-defined plunging angle is achievable with such a construction; plunging is always carried out only with the plunger tools sliding on the stop beam, so that the plunging angle depends on the bracket position and the distance from the soil. Moreover, the brackets are biased against an eccentric shaft by means of a biasing device, which serves to create the up and down movement. This construction is unsuitable for higher speeds, since there is a risk that the brackets are no longer guided on the eccentric disk, at least intermittently, but flung off from the latter. In the context of the plunging function, this entails the risk of extremely hard knocks on the eccentric shaft, which makes faster operation impossible. This is why this apparatus is configured for the walking speed of an operator moving the apparatus.
To make soil treatment quicker and in particular with a defined plunging angle, further developed soil treatment apparatuses have been proposed, as they are described and shown in EP 1 210 853 A1, EP 1 208 730 A1, EP 0 853 869 B1, EP 1 108 350 A1, EP 1 040 741 B1, EP 0 924 975 B1, EP 0 452 449 B1, WO 03/096784 A1, DE 10 2004 018 591 A1 and WO 2006/102869 A1.
These soil treatment apparatuses further developed with respect to the working speed, which are also traversable across the soil in a driving direction, have a plurality of tool units, which also each comprise at least one bracket and at least one plunger tool device. Each of the tool units further has its own stop, however, for the plunger tool device. To enable the plunging movement, the bracket pivots up and down with an end section on the apparatus chassis driven about a first pivoting axis. The plunger tool device is linked on the other end section of the bracket in such a way, that it pivots on the bracket about a second pivoting axis. The stop is formed in such a way that plunging of the plunger tool is carried out at a predefined plunging angle. Driving is by means of a crank drive, the crank linked to the bracket by means of a drive rod.
The soil treatment apparatuses known from the above mentioned references are formed in such a way that the plunger tool is driven into the soil when the bracket is pivoted downward about the first pivoting axis. Herein, the stop of the plunger tool serves to determine the plunging angle. By associating each plunger tool with its own stop the plunging angle can be precisely predetermined and adjusted. As the plunger tool is plunged into the soil and the soil treatment apparatus is driven in the driving direction, the plunger tool device leaves the associated stop due to the resistance in the soil and is pivoted about the second pivoting axis. This is how loosening of the soil is achieved due to pivoting of the plunger tool within the soil. As the bracket is pivoted upward again, the plunger tool is withdrawn from the soil. As soon as it leaves the soil, the plunger tool device, for example due to a biasing device, returns to engagement on the stop. In the soil treatment apparatuses as known from EP 1 108 350 A1, EP 1 040 741 B1, EP 0 924 975 B1 and EP 0 452 449 B1, the stop is arranged to be moved in the area of the second pivoting axis on and together with the other end section of the bracket. In apparatuses as described and shown in principle in EP 0 853 869 B1, a stop resides in the area of a telescopic means moved together with the bracket, which also includes the biasing device.
In all of these faster soil treatment apparatuses, the brackets, with their free end sections, to which the plunger tool is linked, are directed against the driving direction. In other words, the first pivoting axis is in front of the second pivoting axis as seen in the driving direction. The bracket therefore is subjected to tensile stress as the soil treatment apparatus drives on while the plunger tool is stuck in the soil to then withdraw the plunger tool from the soil. This tensile stress has been deemed advantageous in view of a faster operating speed, since fewer shocks overall are transmitted to the apparatus chassis. Attempts have been made, in particular, to absorb these shocks by spring elements to enable even faster operation.
Further approaches for enabling faster operation have been described in WO 2006/102869 A1. Herein, the stop hitherto always moved together with the bracket has been located external to this combined-movement system and is now associated with the fixed chassis. The relative movement of the plunger tool to the bracket is then transmitted by a corresponding drive out of the system pivoted up and down together with the bracket to the fixed system and damped there. This is intended to reduce the moved masses and to make the vibrations in faster operation better manageable. More elaborate damping measures, such as hydraulic damping, thus become possible.